Men tend to have more reddish skin, while greenish skin is more common among women, according to a new study.
After analysing a dozen of faces, Michael J. Tarr, a Brown University scientist, and graduate student Adrian Nestor have discovered that there exists a colour difference associated with gender.
The finding of the study has important implications in cognitive science research, such as the study of face perception, as well as potential industry or consumer applications in areas such as facial recognition technology, advertising, and studies of how and why women apply makeup.
"Colour information is very robust and useful for telling a man from a woman. It's a demonstration that colour can be useful in visual object recognition," said Tarr, the Sidney A. and Dorothea Doctors Fox Professor of Ophthalmology and Visual Sciences and professor of cognitive and linguistic sciences at Brown.
He said that while the idea that colour might be helpful in identifying objects better had been controversial, the new findings showed that colour could nonetheless provide useful information.
For the study, the researchers analysed about 200 images of Caucasian male and female faces (100 of each gender) compiled in a data bank at the Max Planck Institute in Tobingen, Germany, photographed using a 3-D scanner under the same lighting conditions and with no makeup. Also, the researchers used a MatLab program to analyse the amount of red and green pigment in the faces.
Also, the researchers took into account a large number of other faces photographed under similar controlled conditions.
And it was found that men proved to have more red in their faces and women have more green, contrary to prior assumptions.
"If it is on the more red end of the spectrum (the face) had a higher probability of being male. Conversely, if it is on the green end of the spectrum (the face) had a higher probability of being female," said Tarr.
For further testing of the concept, the researchers used an androgynous image compiled from the average of the 200 initial faces. Trial by trial, they randomly clouded the face with "visual noise" that either included more red or green. The "noise" was not unlike static that can appear on a television screen with no signal.
Subjects were then asked to decide on the gender of the image, using nothing more than the random shape and colour patterns over the sexually ambiguous face as a guide. Tarr described the effect as a "superstitious hallucination," similar to being in the shower and hearing the doorbell or telephone even when neither rings.
Even when viewing pixelated or distorted images, subjects identified redder images as male and greener images as female.
The scientists found that observers use the colour of a face when trying to identify its gender. That is particularly true when the shape of the given face is ambiguous or hidden.
Another study found, for example, that observers are quite sensitive to the colour of faces when the facial images are blurred to the point where the face shape is almost impossible to see.
The study, titled "Gender Recognition of Human Faces Using Color," is published online in the journal Psychological Science.